Liquid washing agent compositions that are to be used in washing machines must have a low rate of foaming since excess foaming must be expected with a washing agent composition concentration above 3 to 5 gm per liter. Furthermore, such washing agent compositions are expected to prevent the deposits on heating elements and the wash that are caused by hard water. The latter requirement generally calls for the use of relatively large amounts of condensed phosphates, i.e., complexing agents, an addition that is no longer acceptable for ecological reasons. It was found that only tripolyphosphate, which is relatively difficult to include in liquid concentrates, can effectively prevent the formation of deposits, whereas the pyrophosphate, which is generally used in liquid washing agent compositions because of its better solubility, either does not at all prevent the formation of such deposits or only prevents them to an inadequate degree. When phosphate is not used, the content of tensides with washing action must be considerably increased to obtain a satisfactory washing result. However, a relatively high tenside concentration generally increases the rate of foaming so that the agents are no longer low-foaming in new, automatic washers.
Among the additional properties expected of a liquid washing agent composition by the expert is a water content which is as low as possible to keep the packaging weight down. However, the concentration of active substance cannot be increased at will, since compositions with a content of active substance exceeding 40 weight % tend to separate into phases that frequently become irreversible on cooling of the compositions to temperatures close to the freezing point. Another frequently observed disadvantage of many concentrated liquid washing agent compositions is the fact that the solutions gel, especially upon the addition of water, and can then no longer be uniformly distributed in the wash liquor. These problems can be corrected by the addition of sizable amounts of organic solvents, especially lower alcohols in proportions of more than 8%, but their addition introduces technical problems during the production and utilization of the liquid washing agent composition because of the increased danger of fire or explosions. Even the use of triethanolamine salts, which are readily soluble in water, or the addition of free triethanolamine as solubilizer, does not solve the problem in many cases since triethanolamine salts are more expensive than the sodium salts and triethanolamine, when present in sizable amounts, considerably reduces the effect of bleaches, especially active chlorine or per-acids, due to the consumption of chlorine or oxygen.